1. Field of the Invention
This invention relates to improvements in a computer control system for selecting one control program from a plurality of control programs which output the same kind of signal for the control of an elevator or the like.
2. Description of the Prior Art
In the following explanation, reference will be made to an elevator control system as an example of a system wherein the present invention may be used.
FIGS. 1 and 2 depict a portion of a conventional elevator control system which does not employ computer control. In FIG. 1, a "call" or floor level stop determination circuit for a standard type of an elevator which operates between a first floor and a fifth floor is shown, wherein the reference symbols + and - designate a D.C. (direct current) power source and 1F-4F designate car position relay contacts which close when the car approaches each of the floors 1 to 4. Similarly, car position relay contacts 2G-5G are relay contacts for each of the floors 2 to 5. The reference numerals 1U-4U designate "up call" relay contacts which are closed when the respective "up" buttons at each of the floors 1 to 4 are actuated, 2D-5D designate "down call" relay contacts which are closed when the respective "down" buttons on floors 1 to 5 are actuated, and 6A and 6B designate control relay contacts which are closed during the normal operation of the car. "Up" operation relay contact 7 is closed during the upward operation of the elevator car, and similarly, "down" operation relay contact 8 is closed during the downward operation of the car. "Up" travel relay contact 9 is closed during the travel of the car in the upward direction, and similarly, "down" travel relay contact 10 is closed during the travel of the car in the downward direction. Floor level stop determination relay 11 generates a command signal for stopping the elevator car in response to the actuation of the "call", i.e., up or down buttons arranged at the several floors, when relay 11 is energized.
FIG. 2 illustrates an example of a special type of floor level determination circuit for an elevator which operates between a first and a fifth floor in a mode different from that of FIG. 1.
In FIG. 2, the floor level stop determination relay 11A generates a command signal for stopping the elevator car in response to a "call" when relay 11A is energized. Nonstop relay contacts 12A and 12B are opened when a "nonstop" button in the car is pressed. The other component parts of FIG. 2 are substantially the same as those of FIG. 1, and are accordingly similarly labeled. Depending upon whether the "nonstop" button is depressed, the elevator car will operate in one of two distinct modes, as will be readily understood.
Conventional elevator control circuits are composed of relay circuits such as those shown in FIGS. 1 and 2. The number of relays employed in a typical elevator is about one hundred. The number of relays employed in a sophisticated elevator may be several hundred. The standardization of these relay circuits has progressed somewhat, and the majority of elevators in use today can be controlled by standardized circuits. However, some existing elevators still need special circuits.
The operation of the conventional relay circuits will now be described with reference to FIGS. 1 and 2.
In FIG. 1, when a "up" call is made at, for instance, the third floor and the car, in normal operation, is travelling in the upward direction approaching the third floor, floor level stop determination relay 11 is energized by the circuit (+)-3F-3U-6A-9-11-(-), and the car commences deceleration for stopping at the third floor in accordance with known car stopping and leveling circuitry (not shown).
When the car is travelling in the upward direction and no "up" call is made, and therefore upward operation is not needed, "up" operation relay contact 7 is closed, and the car is stopped by the circuit (+)-7-9-11-(-).
In the majority of elevators, the circuit in FIG. 1 performs the floor level stopping determination. However, in a manually operated elevator, which is fitted with a nonstop button, the circuit shown in FIG. 2, containing partial changes to the standard circuit, is necessary.
In FIG. 2, when an "up" call is made at the third floor, and the car, in normal operation, is travelling in the upward direction approaching the third floor, if the nonstop button is pressed, floor level stop determination relay 11A will not be energized because nonstop relay contact 12A is open, and the car thus passes the third floor without stopping.
Thus, when the elevator is required to operate in a manner different from the standard operation, modifications to the elevator control circuit are necessary. These modifications, such as the addition of a "nonstop" mode, may be effected by the addition of further switches and relays to the standard control circuit.
In recent years, the use of electronic computers has become widespread, as have elevator control circuits composed of electronic computers, for use in elevators ranging from the more sophisticated types down to the more basic models.
In computerizing elevator control circuits, the computer programs have been patterned after the same circuitry used in the conventional relay circuits due to considerations of familiarity with the old system among the many parties concerned with the design, erection, and maintenance of the elevator systems.
FIG. 3 shows a typical prior art computer control system for an elevator.
In FIG. 3, a central processing unit (CPU) 21 executes in sequence the programs of read only memories (ROMs) 22A-22C, in which have been stored the elevator control programs. In random access memory (RAM) 23 is stored the ON/OFF data corresponding to the relay contacts and relay coils shown in FIGS. 1 and 2. The reference numerals 24 and 25 designate a data bus and an address bus which transfer the data between ROMs 22A-22C, RAM 23 and CPU 21. Input circuit 30 inputs ON/OFF state signals of various relay contacts and coils concerning the elevator, and generates input data. Signals from input terminals 31 and 31a to 31n are stored in RAM 23 as shown in FIG. 4 by the control of CPU 21 via the data bus 24 and the address bus 25.
ROMs 22a to 22c are constituted by 3 ROM IC devices of the 2716 type (16K (2K.times.8) UV Erasable PROM) manufactured by Intel.
The number of ROM IC devices may increase or decrease in accordance with the quantity of control programs, and in this case, 3 ROM IC devices have been determined to be necessary. Included in ROMs 22a to 22c are the various control programs for floor level stop determination, car running direction determination, door control, hall and in-car car position indicator control, and so on.
The CPU 21 is an 8085A type device manufactured by Intel. With regard to the operation of this device, reference should be made to the "MCS-85.TM. USER'S MANUAL" published by Intel, wherein detailed explanation is to be found.
FIG. 4 shows stored data corresponding to the ON/OFF state signals of the relay contacts and coils shown in FIG. 3.
Output circuit 35 receives control data stored in RAM 23 by the control of CPU 21 via data bus 24 and address bus 25, and generates output signals for controlling motors, power sources and ON/OFF relays corresponding to output terminals 36, 36a-36n.
A floor level stop determination program corresponding to the circuit shown in FIG. 1 employed as the computer control system for the elevator is illustrated in FIG. 5. FIG. 5 shows a flow chart corresponding to this program, which is stored together with an address in ROM 22A.
In FIG. 5, each of the designated registers A, B and C temporarily a store data and are installed in CPU 21. Reference symbol V designates logical addition, designates logical multiplication, .fwdarw. designates data flow for writing in a memory or register, a bar across the top of an item of data (e.g., contact 7 data) designates the complement of the data.
For example, the execution of the 13th step "contact 7 data V register A data.fwdarw.register A" is as follows: contact 7 data (i.e., "ON" or "OFF") stored in RAM 23 is read out and the complement thereof is taken. The complement data and the data stored in register A are logically added, and the addition data is written in register A. The executions of the remaining steps are similar to the execution of the 13th step, and therefore are not further explained herein.
In general, in accordance with the programs stored in ROM 22A, CPU 21 reads data corresponding to relay contacts 1F-4F, 2G-5G, 1U4U, 2D-5D, 6A-6B, and 6-10, which are stored in RAM 23, and executes operations such as AND or OR corresponding to the circuit shown in FIG. 1, and stores the resulting data, such as that corresponding to the state of relay coil 11, in RAM 23. In the same way, CPU 21 executes other programs, and periodically (50 m-100 m sec) executes the programs stored in ROMs 22A-22C.
An example of the operation of the foregoing might be where an elevator car is in the vicinity of the second floor and is moving in the upward direction. Then, at that moment, the `UP` button on the third floor is pressed. Pressing this button provides an input to the input circuit 30, and during the period thereof, a third floor `UP` call data is recorded in RAM 23 by CPU. That is to say, the closure of contact 3U is indicated in RAM 23. The car continues to travel upwards, and when it trips a cam switch (not shown) provided, for instance, in the hoistway, which switch indicates proximity to the third floor, this signal is in the same way as above said inputted by input circuit 30, and the contact in RAM 23 shows ON data. Generally the elevator control cycle for the CPU takes about 50-100 m sec, and in the next period after the 3F contact closes, the coil 11 is energized (as shown in the flow chart of FIG. 5) because contacts 3F and 3U are closed. When the coil 11 is energized, a corresponding signal is outputted via the output circuit 35 and, accordingly, is made to decelerate the motor.
If the standard circuit is modified to achieve the functions of the special circuit shown in FIG. 2, the relay contacts 12A and 12B enter into the scheme, and so the program will be as shown in FIG. 6, differing slightly from the standard program shown in FIG. 5. In the program of FIG. 6, steps 61 and 62 are added to the standard program in FIG. 5.
In this way, if the standard program stored in ROM 22A needs to be rewritten to a modification thereof, ROM 22A as well as ROM 22B and 22C will have to be completely changed because of the necessity of the changing the addresses for the programs stored therein.
In other words, if the program is to be modified slightly from standard, the majority of the programs stored in the ROMs can no longer be used and so special programs (i.e., special ROMs) must be used. Accordingly, in order to provide a complete system wherein hardware failures can be quickly remedied, spares of all the special types of ROMs must be kept on hand. Further, there is the disadvantage that the cost is increased if there are many "specialty" parts, as stated above.